A 23-year-old woman developed a fatal blood clot weeks after starting to take the contraceptive pill, an inquest has heard.

A friend found Lauren Johnson semi-conscious in bed at her home at Castle Grove, Swords, Co Dublin, on September 3, 2015. She died from a blood clot and associated brain haemorrhage at Beaumont Hospital four days later.

Ms Johnson, known to her family and friends as 'Rosy', was working as a Japanese translator at the time of her death. An inquest into her death at Dublin Coroner's Court heard she had been suffering from persistent headaches in the weeks leading up to her death and had visited her GP on September 1 complaining of a headache and visual disturbance.

"She complained a lot about this headache that wouldn't go away," said her best friend, Kevin Gannon.

He became concerned when he got no reply to his texts and calls. He called to Ms Johnson's house and found her in bed. "She was groggy and couldn't string a sentence together," he said. An ambulance was called.

"They asked her if she had taken tablets before and she replied yes, but she had never done that before," he said.

There was a packet of paracetamol with 16 tablets missing at the house. Family members said she had been taking paracetamol for her headaches. Paramedics rushed her to Beaumont. On a handover sheet for hospital staff, they wrote 'query overdose'.

She was admitted with a suspected paracetamol overdose at 1.35pm on September 3. Dr Farah Mustafa saw Ms Johnson at 1.50pm and said the patient was drowsy but her vital signs were normal. She ordered a blood test and a review by a psychiatrist.

At 6.50pm, the psychiatrist approached the doctor, having spoken to Ms Johnson's friends waiting in A&E. "When he expressed concern that she hadn't seen psychiatric services in Beaumont before, that made me concerned," Dr Mustafa said.

Further tests revealed a blood clot in the brain.

Ms Johnson's parents Brian and Sandra Johnson, who were in Portugal, rushed home to be at her bedside. Consultant neurologist at Beaumont Dr Lisa Costello said Ms Johnson had a blood clot that entered the brain and she suffered an associated haemorrhage.

Ms Johnson's GP records revealed she had started taking the contraceptive pill in July 2015. Blood clots in the veins are a known risk factor for the contraceptive pill. Her mother said there was a higher risk associated with the particular brand her daughter was taking and asked for further evidence.